The subject matter disclosed herein generally relates to acoustic treatments and, more particularly, to acoustic treatment of structural fittings, such as hinge and latch beams, in aircraft engine nacelles.
Commercial jet aircraft typically include turbofan propulsion systems comprising a turbofan engine housed in a nacelle. The major components of a nacelle may include an inlet, a fan cowl, a thrust reverser, and an exhaust assembly. Among other functions, the nacelle provides aerodynamic fairings that surround the propulsion system to reduce drag and provides a nozzle for the core from the engine and the bypass air from the fan. The thrust reverser produces reverse thrust to slow the aircraft upon landing. The inlet, thrust reverser, and exhaust assembly may also include acoustic treatments to help attenuate noise generated by the engine. For example, the thrust reverser, which helps define the duct for the fan bypass air, may be constructed in part with acoustic sandwich panels that attenuate noise emanating from the fan. Much of the internal surface of the bypass duct formed by the thrust reverser is formed with these acoustic panels to help significantly reduce the noise. However, a portion of the duct inner surface in a typical modern thrust reverser remains acoustically untreated. Adding acoustic treatments to the presently untreated surfaces is an opportunity to further reduce aircraft engine noise.
The acoustically untreated surfaces today inside a thrust reverser bypass duct include surfaces formed by the twelve o'clock and six o'clock hinge and latch beams, and surfaces surrounding bleed air exhaust ports, and air-cooled oil cooler cooling air scoops. These structures are not made with sandwich panels, so applying acoustic treatments to them has been more difficult. The present disclosure offers an option for applying acoustic treatments to hinge and latch beams and similar structures or fittings that make up part of the air flow surfaces on a nacelle.